chapter 23 invertebrate diversity. 23.4 flatworms, mollusks, annelids a. body plan of flatworms:...

Chapter 23

Invertebrate Diversity

23.4 Flatworms, Mollusks, Annelids

A. Body Plan of Flatworms: solid body with an incomplete or

absent gut; flatB. Form & Function in Flatworms: 1. Feeding: gastrovascular cavity

with a tube called a pharynx; intestines branch in body; undigested food out through mouth

2. Respiration: diffusion


B. Form & Function in Flatworms: 3. Internal Transport: none 4. Excretion: diffusion 5. Response: simple brain and

nerves; eyespots sense light; sensors for food

6. Movement: cilia to glide through water and muscles to twist and turn


B. Form & Function in Flatworms: 7. Reproduction: sexual or

asexual; hermaphrodites; regeneration

8. Habitat: fresh and salt water, land

9. Examples: Planarians

Planarian

Marine FlatwormsMarine Flatworms


B. Form & Function in Parasitic Flatworms: 1. Feeding: some have a pharynx;

others absorb food 2. Respiration: diffusion 3. Internal Transport: none 4. Excretion: diffusion 5. Response: not much 6. Movement: cilia, ?


B. Form & Function in Parasitic Flatworms: 7. Reproduction: complicated,

sexual life cycles 8. Habitat: in host 9. Examples: flukes, tapeworms;

have suckers on head and attach to intestines; uncooked meat


C. What are mollusks? soft-bodied animals that have an

internal or external shellD. Body Plan of Mollusks: 1. foot: muscular; usually contains

the mouth

Snail Foot

Octopus Foot

Clam Foot


D. Body Plan of Mollusks: 2. mantle: thin tissue layer that

covers most of body 3. shell: made of CaCO3

4. visceral mass: beneath mantle, contains internal organs

Mollusk Comparison


E. Form & Function in Mollusks: 1. Feeding

a. complete digestive tract: food enters mouth, digested in gut, absorbed, waste out anus

b. radula: used to scrape plants (snails, slugs)

c. gills: used to filter feed (bivalves)

Radula


E. Form & Function in Mollusks: 2. Respiration

a. gillsb. moist mantle cavity (land snails)

3. Internal Transporta. open circulatory system: blood flows in cavities (snails and slugs)

b. closed circulatory system: blood flows in vessels (octopi and squids)


E. Form & Function in Mollusks: 4. Excretion

a. nephridia: remove ammonia from blood

5. Responsea. simple: clam—nerves, chemical and touch receptors, eyespots

b. complex: octopus—well-developed brain capable of memory and learning


E. Form & Function in Mollusks: 6. Movement: crawling,

swimming, jet propulsion 7. Reproduction

a. separate sexes and external fertilization (snails and bivalves)

b. internal fertilization (tentacled mollusks and certain snails)


F. Mollusk Classes 1. Gastropods: Snails and Slugs

a. gastropod: “stomach foot”b. one-piece shell (except slugs)c. use hiding, swimming, or poison for protection

Sea Slug

Banana Slug

Giant Land Snails


F. Mollusk Classes 2. Bivalves: Two-Shelled Mollusks

a. bivalve: “two shell”b. shells hinged at backc. Examples: clams, oysters, and scallops

d. usually sessile


F. Mollusk Classes 3. Cephalopods: Tentacled

Mollusksa. cephalopod: “head foot”b. Examples: octopi, squids, nautiluses

c. usually have 8 tentacles with suckers for grabbing prey


F. Mollusk Classes 3. Cephalopods: Tentacled

Mollusksd. swim or squirt ink for protection; octopi can change color to match surroundings


G. What are annelids? round, wormlike animal that has a

long, segmented body


H. Form & Function in Annelids: 1. Feeding

a. complete digestive tractb. eat waste; some are filter feeders

2. Respirationa. gillsb. moist skin

3. Internal Transporta. closed circulatory system w/ multiple hearts


H. Form & Function in Annelids: 4. Excretion

a. nephridia 5. Response:

a. brain and nervesb. sensory tentacles, chemical receptors, eyes

c. Protection: poisons, burrows, swimming, biting

Tube Worm


H. Form & Function in Annelids: 6. Movement

a. longitudinal muscles: cause the worm to shorten

b. circular muscles: make the worm skinnier

c. hydrostatic skeleton


H. Form & Function in Annelids: 7. Reproduction

a. sexual or asexualb. some separate sexes and external fertilization

c. some hermaphrodites and internal fertilization (earthworms)

Osedax on Whale Bone

chapter 23 invertebrate diversity. 23.4 flatworms, mollusks, annelids a. body plan of flatworms:...

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